// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// A template for a simple rectangle class.  The containment semantics
// are array-like; that is, the coordinate (x, y) is considered to be
// contained by the rectangle, but the coordinate (x + width, y) is not.
// The class will happily let you create malformed rectangles (that is,
// rectangles with negative width and/or height), but there will be assertions
// in the operations (such as Contains()) to complain in this case.

#ifndef UI_GFX_GEOMETRY_RECT_BASE_H_
#define UI_GFX_GEOMETRY_RECT_BASE_H_

#include <string>

#include "base/compiler_specific.h"

namespace gfx {

template <typename Class,
    typename PointClass,
    typename SizeClass,
    typename InsetsClass,
    typename VectorClass,
    typename Type>
class GFX_EXPORT RectBase {
public:
    Type x() const { return origin_.x(); }
    void set_x(Type x) { origin_.set_x(x); }

    Type y() const { return origin_.y(); }
    void set_y(Type y) { origin_.set_y(y); }

    Type width() const { return size_.width(); }
    void set_width(Type width) { size_.set_width(width); }

    Type height() const { return size_.height(); }
    void set_height(Type height) { size_.set_height(height); }

    const PointClass& origin() const { return origin_; }
    void set_origin(const PointClass& origin) { origin_ = origin; }

    const SizeClass& size() const { return size_; }
    void set_size(const SizeClass& size) { size_ = size; }

    Type right() const { return x() + width(); }
    Type bottom() const { return y() + height(); }

    PointClass top_right() const { return PointClass(right(), y()); }
    PointClass bottom_left() const { return PointClass(x(), bottom()); }
    PointClass bottom_right() const { return PointClass(right(), bottom()); }

    VectorClass OffsetFromOrigin() const
    {
        return VectorClass(x(), y());
    }

    void SetRect(Type x, Type y, Type width, Type height);

    // Shrink the rectangle by a horizontal and vertical distance on all sides.
    void Inset(Type horizontal, Type vertical)
    {
        Inset(horizontal, vertical, horizontal, vertical);
    }

    // Shrink the rectangle by the given insets.
    void Inset(const InsetsClass& insets);

    // Shrink the rectangle by the specified amount on each side.
    void Inset(Type left, Type top, Type right, Type bottom);

    // Move the rectangle by a horizontal and vertical distance.
    void Offset(Type horizontal, Type vertical);
    void Offset(const VectorClass& distance)
    {
        Offset(distance.x(), distance.y());
    }
    void operator+=(const VectorClass& offset);
    void operator-=(const VectorClass& offset);

    InsetsClass InsetsFrom(const Class& inner) const
    {
        return InsetsClass(inner.y() - y(),
            inner.x() - x(),
            bottom() - inner.bottom(),
            right() - inner.right());
    }

    // Returns true if the area of the rectangle is zero.
    bool IsEmpty() const { return size_.IsEmpty(); }

    // A rect is less than another rect if its origin is less than
    // the other rect's origin. If the origins are equal, then the
    // shortest rect is less than the other. If the origin and the
    // height are equal, then the narrowest rect is less than.
    // This comparison is required to use Rects in sets, or sorted
    // vectors.
    bool operator<(const Class& other) const;

    // Returns true if the point identified by point_x and point_y falls inside
    // this rectangle.  The point (x, y) is inside the rectangle, but the
    // point (x + width, y + height) is not.
    bool Contains(Type point_x, Type point_y) const;

    // Returns true if the specified point is contained by this rectangle.
    bool Contains(const PointClass& point) const
    {
        return Contains(point.x(), point.y());
    }

    // Returns true if this rectangle contains the specified rectangle.
    bool Contains(const Class& rect) const;

    // Returns true if this rectangle intersects the specified rectangle.
    // An empty rectangle doesn't intersect any rectangle.
    bool Intersects(const Class& rect) const;

    // Computes the intersection of this rectangle with the given rectangle.
    void Intersect(const Class& rect);

    // Computes the union of this rectangle with the given rectangle.  The union
    // is the smallest rectangle containing both rectangles.
    void Union(const Class& rect);

    // Computes the rectangle resulting from subtracting |rect| from |*this|,
    // i.e. the bounding rect of |Region(*this) - Region(rect)|.
    void Subtract(const Class& rect);

    // Fits as much of the receiving rectangle into the supplied rectangle as
    // possible, becoming the result. For example, if the receiver had
    // a x-location of 2 and a width of 4, and the supplied rectangle had
    // an x-location of 0 with a width of 5, the returned rectangle would have
    // an x-location of 1 with a width of 4.
    void AdjustToFit(const Class& rect);

    // Returns the center of this rectangle.
    PointClass CenterPoint() const;

    // Becomes a rectangle that has the same center point but with a size capped
    // at given |size|.
    void ClampToCenteredSize(const SizeClass& size);

    // Splits |this| in two halves, |left_half| and |right_half|.
    void SplitVertically(Class* left_half, Class* right_half) const;

    // Returns true if this rectangle shares an entire edge (i.e., same width or
    // same height) with the given rectangle, and the rectangles do not overlap.
    bool SharesEdgeWith(const Class& rect) const;

    // Returns the manhattan distance from the rect to the point. If the point is
    // inside the rect, returns 0.
    Type ManhattanDistanceToPoint(const PointClass& point) const;

    // Returns the manhattan distance between the contents of this rect and the
    // contents of the given rect. That is, if the intersection of the two rects
    // is non-empty then the function returns 0. If the rects share a side, it
    // returns the smallest non-zero value appropriate for Type.
    Type ManhattanInternalDistance(const Class& rect) const;

protected:
    RectBase(const PointClass& origin, const SizeClass& size)
        : origin_(origin)
        , size_(size)
    {
    }
    explicit RectBase(const SizeClass& size)
        : size_(size)
    {
    }
    explicit RectBase(const PointClass& origin)
        : origin_(origin)
    {
    }
    // Destructor is intentionally made non virtual and protected.
    // Do not make this public.
    ~RectBase() { }

private:
    PointClass origin_;
    SizeClass size_;
};

} // namespace gfx

#endif // UI_GFX_GEOMETRY_RECT_BASE_H_
